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Warm, stale air is exhausted at the ceiling|Diagram of air movement in an underfloor air distribution system]] '''Underfloor air distribution''' (UFAD) is an air distribution strategy for providing [[Ventilation (architecture)|ventilation]] and space conditioning in [[building]]s as part of the design of a [[HVAC]] system. UFAD systems use an underfloor supply [[plenum chamber|plenum]] located between the structural concrete slab and a [[raised floor]] system to supply conditioned air to supply outlets (usually floor diffusers), located at or near floor level within the occupied space. Air returns from the room at ceiling level or the maximum allowable height above the occupied zone.<ref name=":1">{{cite book |last1=Bauman |first1=Fred S. |title=Underfloor Air Distribution (UFAD) Design Guide |last2=Daly |first2=Allan |date=2003 |publisher=American Society of Heating, Refrigerating and Air-Conditioning Engineers |isbn=978-1-931862-21-9 |oclc=54615153}}</ref> The UFAD system takes advantage of the thermal [[Plume (fluid dynamics)|plume]] and stratification phenomenon: the conditioned air is supplied directly to the occupied zone (OZ). The thermal plumes generated by the occupants and other heat sources introduce the conditioned air to absorb the heat and humidity and then bring the contaminated air to the upper zone (UZ). At a certain plane in the room, the airflow rate returned to the upper zone is equal to the supply air. The plane divides the room into occupied zone and upper zone and leads to thermal stratification: the hot and contaminated air is concentrated in the upper zone, and the air in the occupied zone is cool and fresh.<ref>{{Cite journal |last1=Zhang |first1=Kai |last2=Zhang |first2=Xiaosong |last3=Li |first3=Shuhong |last4=Jin |first4=Xing |date=2014-12-01 |title=Review of underfloor air distribution technology |url=https://www.sciencedirect.com/science/article/pii/S0378778814007014 |journal=Energy and Buildings |language=en |volume=85 |pages=180–186 |doi=10.1016/j.enbuild.2014.09.011 |issn=0378-7788}}</ref> UFAD can bring several potential advantages over traditional overhead systems, including reduced life-cycle building costs; improved thermal comfort, occupant satisfaction, and productivity; improved ventilation efficiency, [[indoor air quality]], and health; reduced energy use and static pressures; and reduced floor-to-floor height in new construction.<ref>{{Cite journal |last1=Bauman |first1=Fred |last2=Webster |first2=Tom |date=Jun 2001 |title=Outloof of underfloor air distribution |journal=ASHRAE Journal |volume=43 |issue=6}}</ref> An under-floor air distribution concept combined with a ceiling-distributed returns ventilation layout (UFAD-CDR) can dramatically reduce the risk of airborne transmission at both high and low ACHs.<ref>{{cite journal |last1=Zabihi |first1=Mojtaba |last2=Li |first2=Ri |last3=Brinkerhoff |first3=Joshua |title=Influence of indoor airflow on airborne disease transmission in a classroom |journal=Building Simulation |date=1 March 2024 |volume=17 |issue=3 |pages=355–370 |doi=10.1007/s12273-023-1097-y |url=https://link.springer.com/article/10.1007/s12273-023-1097-y |language=en |issn=1996-8744}}</ref> The UFAD system was originally introduced in the 1950s for rooms with high heat loads and [[raised floor]]s systems for cable and equipment management (e.g. computer rooms, control centers, etc.). The system was introduced into office buildings in the 1970s in West Germany, with the addition of occupant-controlled localized supply diffusers. Nowadays UFAD system has achieved considerable acceptance in Europe, South Africa, and Japan.<ref name=":1" /> UFAD is often used in [[office building]]s, particularly highly-reconfigurable and open plan offices where [[raised floor]]s are desirable for cable management. UFAD is appropriate for a number of different building types including commercials, schools, churches, airports, museums, libraries, etc.<ref name="UFAD Guide 2013">{{cite book|last=ASHRAE Technical Resource Group On Underfloor Air Design|title=UFAD GUIDE Design, Construction and Operation of Underfloor Air Distribution Systems|year=2013|publisher=W. Stephen Comstock|isbn=978-1-936504-49-7|url=http://www.techstreet.com/ashrae/products/1859223#jumps}}</ref> Notable buildings using the UFAD system in North America include [[The New York Times Building]], [[Bank of America Tower (New York City)|Bank of America Tower]] and [[San Francisco Federal Building]]. Careful considerations need to be made in the construction phase of UFAD systems to ensure a well-sealed plenum to avoid air leakage in UFAD supply plenums. ==System description== UFAD systems rely on [[Air handler|air handling units]] to filter and condition air to the appropriate supply conditions so it can be delivered to the occupied zone. While overhead systems typically use [[Duct (HVAC)|duct]]s to distribute the air, UFAD systems use the underfloor plenum formed by installation of a [[raised floor]]. The plenum generally sits {{convert|0.3|and|0.46|m|in|lk=on}} above the structural concrete slab, although lower heights are possible.<ref name="Hanzawa">{{Citation | title = Air flow distribution in a low-height underfloor air distribution plenum of an air conditioning system | year = 1996| journal = AIJ Journal of Technology and Design| volume = 3|pages=200–205 |last1= Hanzawa |first1=H.|last2=Higuci|first2=M.| doi = 10.3130/aijt.2.200|doi-access= free}}</ref><ref name="BaumanPecora">{{Citation | title = How low can you go? Air flow performance of low-height underfloor plenums | year = 1999| publisher=Center for the Built Environment, UC Berkeley| url=http://escholarship.org/uc/item/5rx3p5w4 |last1= Bauman |first1=Fred|last2=Pecora|first2=Paolo|last3=Webster|first3=Tom}}</ref> Specially designed floor [[Diffuser (thermodynamics)#HVAC|diffusers]] are used as the supply outlets.<ref name="UFAD Guide 2013" /> The most common UFAD configuration consists of a central air handling unit delivering air through a pressurized plenum and into the space through floor diffusers. Other approaches may incorporate fan powered [[Duct (HVAC)#Terminal units|terminal units]] at the outlets, underfloor ducts, desktop vents or connections to [[Personal Environmental Control Systems]].<ref name="design guide"/> ==UFAD air distribution and stratification== Thermal stratification is the result of processes which layer the internal air in accordance with relative density. The resulting air stratum is a vertical gradient with high-density and cooler air below and low-density and warmer air above.<ref name="Nielsen">{{Citation | last =Nielsen | first =P. V. | title =Displacement Ventilation – Theory and Design | journal =U | volume =U9513 | year =1996 | issn =0902-8005 | publisher =Department of Building Technology and Structural Engineering, Aalborg University}}</ref> Due to the naturally convective movement of air, stratification is used predominantly in cooling conditions.<ref name="Nielsen"/> [[File:UFAD Air Stratification Example Diagram.jpg|thumb|Air stratification capitalizes on thermal buoyancy to layer high quality supply air at occupant level and leave unoccupied air unconditioned.]] UFAD systems capitalize on the natural stratification that occurs when warm air rises due to [[Stack effect|thermal buoyancy]]. In a UFAD design, conditioned air stays in the lower, occupied part of the room, while heat sources such as occupants and equipment generate [[Plume (hydrodynamics)#Heat|thermal plumes]], which carry the warm air and heat source generated pollutants towards the [[ceiling]] where they are exhausted through the return air ducts.<ref name="design guide"/> The temperature stratification created by the UFAD system has implication for space setpoints. Most of an occupant's body is in an area that is colder than the temperature at the thermostat height; therefore, current practice recommends raising thermostat setpoints compared to traditional overhead systems. The optimal ventilation strategy controls the supply outlets to limit the mixing of supply air with room air to just below the breathing height of the space. Above this height, stratified and more polluted air is allowed to occur. The air that the occupant breathes will have a lower concentration of contaminants compared to conventional uniformly mixed systems.<ref name="design guide" /> The theoretical behavior of UFAD systems is based on the plume theory for [[Displacement ventilation|DV systems]]. In comparison to classic displacement ventilation (DV) systems <ref name="Nielsen"/> that deliver air at low velocities, typical UFAD systems deliver air through floor diffusers with higher supply air velocities. In addition to increasing the amount of mixing (and therefore potentially diminishing the ventilation performance compared to DV systems), these more powerful supply air conditions can have significant impacts on room air stratification and thermal comfort in the occupied zone. Therefore, the control and optimization of this stratification is crucial to system design and sizing, energy-efficient operation, and comfort performance of UFAD systems.<ref name=":0">{{cite journal |last1=Webster |first1=T. |last2=Bauman |first2=Fred |last3=Reese |first3=J. |title=Underfloor air distribution: thermal stratification |journal=ASHRAE Journal |date=2002 |volume=44 |issue=5 |url=https://escholarship.org/uc/item/9145t9gz}}</ref> Many factors, including the ceiling height, diffuser characteristics, number of diffusers, supply air temperature, total flow rate, cooling load and conditioning mode affect the ventilation efficiency of UFAD systems.<ref name="Lee">{{Citation | title = Air distribution effectiveness with stratified air distribution | year = 2009| journal = ASHRAE Transactions| volume = 115 | issue = 2 | last1 = Lee | first1 = K.S. | last2 = Jiang | first2 = Z. | last3 = Chen | first3 = Q. }}</ref> Swirl and perforated-floor-panel diffusers have been shown to create a low air velocity in the occupied zone, while linear diffusers created the highest velocity in the occupied zone, disturbing thermal stratification and posing a potential draft risk.<ref name="Lee"/> Additionally, floor diffusers add an element of personal control within the reach of the occupant, as users can adjust the amount of air that is delivered by the diffuser though rotating the diffuser top. ==Application Characteristics== ===UFAD cooling load=== [[File:CoolingLoadUFADvsOH.png|thumb|350px|Schematic flow diagram of calculation procedure showing transformation from cooling load calculated for an overhead mixing system into a UFAD cooling load, and then divided between the supply plenum, zone (room), and return plenum.]] Cooling load profiles for UFAD systems and overhead systems are different,<ref name="Simplified calculation method for design cooling loads in underfloor air distribution (UFAD) systems">{{cite journal|last=Schiavon|first=Stefano|author2=Lee, Kwang Ho |author3=Bauman, Fred |author4=Webster, Tom |title=Simplified calculation method for design cooling loads in underfloor air distribution (UFAD) systems|journal=Energy and Buildings|date=February–March 2011|volume=43|issue=2–3|pages=517–528|doi=10.1016/j.enbuild.2010.10.017|url=http://www.escholarship.org/uc/item/5w53c7kr}}</ref> mainly due to the thermal storage effect of the lighter-weight raised floor panels compared to the heavier mass of a structural floor slab. The mere presence of the raised floor reduces the ability of the slab to store heat, thereby producing for the system with a raised floor higher peak cooling loads compared to the system without a raised floor. In the OH system, particularly in perimeter zones, part of the incoming solar heat gain is stored in the floor slab during the day, thus reducing peak zone cooling loads, and released at night when the system is off. In a UFAD system, the presence of the raised flooring transforms the solar absorbing massive floor slab into a lighter weight material, leading to relatively higher peak zone cooling loads.<ref name="UFAD Guide 2013"/> A modeling study based on EnergyPlus simulations showed that, generally, UFAD has a peak cooling load 19% higher than an overhead cooling load and 22% and 37% of the total zone UFAD cooling load goes to the supply plenum in the perimeter and interior, respectively.<ref name="SchiavonUFADdesigntool">{{Citation | title = Simplified calculation method for design cooling loads in underfloor air distribution (UFAD) systems | url = http://escholarship.org/uc/item/5w53c7kr | year = 2011 | journal = Energy and Buildings | volume = 43 | issue = 2|pages=517–528 | doi = 10.1016/j.enbuild.2010.10.017 |last1= Schiavon |first1=Stefano|last3=Bauman |first3=Fred |last4=Webster| first4=Tom|last2=Lee|first2=Kwang Ho}}</ref> Center for the Built Environment developed a new index UFAD cooling load ratio (UCLR), which is defined by the ratio of the peak cooling load calculated for UFAD to the peak cooling load calculated for a well-mixed system, to calculate the UFAD cooling load for each zone with the traditional peak cooling load of an overhead (well-mixed) system. UCLR is determined by zone type, floor level and the zone orientation. The Supply Plenum Fraction (SPF), Zone Fraction (ZF) and Return Plenum Fraction (RPF) are developed similarly to calculate the supply plenum, zone and return plenum cooling load.<ref name="Simplified calculation method for design cooling loads in underfloor air distribution (UFAD) systems"/> ===UFAD design tools for zone airflow requirements=== There are two available design tools for determining zone airflow rate requirements for UFAD system, one is developed at [[Purdue University]] as part of the [[ASHRAE]] Research Project (RP-1522).<ref>{{cite journal|last=Lee|first=Kisup|author2=Xue, Guangqing|title=Establishment of Design Procedures to Predict Room Airflow Requirements in Partially Mixed Room Air Distribution Systems|journal=ASHRAE Research Project Report RP-1522|date=June 2012}}</ref> The other one is developed at [[Center for the Built Environment]] (CBE) at [[University of California Berkeley]]. ASHRAE Research Project (RP-1522) developed a simplified tool that predicts the vertical temperature difference between the head and ankle of occupants, the supply air flow rate for one plenum zone, number of diffusers and the air distribution effectiveness. The tool requires users to specify the zone cooling load and the fraction of the cooling load assigned to the underfloor plenum. It also requires users to input the supply air temperature either at the diffuser or at the duct but with the ratio of plenum flowrate to zonal supply flowrate. The tool allows users to select from three type of diffusers and is applicable to seven type of buildings, including office, classroom, workshop, restaurant, retail shop, conference room and auditorium.<ref name="design guide"/><ref>{{cite journal|last=Xue|first=Guangqing|author2=Lee, Kisup |author3=Jiang, Zheng |author4= Chen, Qingyan |title=Thermal environment in indoor spaces with under-floor air distribution systems: Part 2. Determination of design parameters (1522-RP)|journal=HVAC&R Research|year=2012|volume=18|issue=6 |pages=1192–1201|doi=10.1080/10789669.2012.710058|s2cid=15848165 }}</ref> The CBE UFAD design tool based on extensive research is able to predict the cooling load for UFAD system with the input of the design cooling load calculated for the same building with an overhead system. It also predicts the airflow rate, room temperature stratification, and the plenum temperature gain for both interior and perimeter zones of a typical multi-story office buildings using UFAD system. The CBE tool allows the user to select from four different plenum configurations (series, reverse series, independent and common) and three floor-diffusers (swirl, square and linear bar grill). An online version of the design tool is publicly available at [http://www.cbe.berkeley.edu/ufad-designtool/online.htm Center for the Built Environment]. ===Plenum air temperature rise=== [[File:UfadHeatTransfer.png|thumb|350px|Heat transfer pathways in UFAD system.]] Plenum supply air temperature rise is the increase of the conditioned air due to convective heat gain as it travels through the underfloor supply plenum from the plenum inlet to the floor diffusers.<ref name="Thermal decay"/> This phenomenon is also named thermal decay. Plenum air temperature rise is caused by cool supply air coming into contact with warmer than air concrete slab and raised floor. According to a modeling study, air temperature rise can be quite significant (as much as 5&nbsp;°C or 9&nbsp;°F) and subsequently, compared to an idealized simulated UFAD case with no air temperature rise, elevated diffuser air temperatures can lead to higher supply airflow rate and increased fan and chiller energy consumption. The same study found that air temperature rise in summer is higher than in winter and it also depends on the climate.<ref name="Thermal decay"/> The ground floor with a slab on grade has less temperature rise compared to middle and top floors, and an increase of the supply air temperature causes a decrease in the temperature rise. The temperature rise is not significantly affected by the perimeter zone orientation, the internal heat gain and the window-to-wall ratio.<ref name="Thermal decay"/> Supply plenum air temperature rise, thus, has implications on the energy saving potential of UFAD systems and their ability to meet cooling requirements with supply temperatures above those of conventional overhead systems. Current research suggests that both energy and thermal performance can be improved in UFAD systems by ducting air to perimeter zones where loads tend to be the greatest.<ref name="Thermal decay"/> Critics suggest however that such underfloor ducting reduces the benefit of having a low-pressure plenum space, as well as adding design and installation complications when fitting ducts between floor tile pedestals. ===Air leakage in UFAD plenums=== [[File:UfadLeakageBad.png|thumb|left|300px|UFAD leakage that does not contribute to cooling, leading to wasted increased fan energy.]] [[File:UfadLeakageGood.png|thumb|300px|UFAD leakage into the space, contributing to cooling.]] Leakage in UFAD supply plenums can be a major cause for inefficiency in a UFAD system. There are two types of leakage—leakage into the space and leakage into pathways that bypass the space. The first category of leakage does not result in an energy penalty because air is getting to the zone it is intended to cool. The second category of leakage increases fan energy in order to maintain a constant plenum pressure, resulting in increased energy use. Careful consideration needs to be paid in the construction phase of UFAD systems to ensure a well-sealed plenum.<ref name="design guide" /> ===UFAD and energy=== The energy assessment of UFAD systems has not been extensive, but some studies indicates potential energy savings due the lower pressure drop and lower air flow rate. Typical plenum pressures are {{convert|25|Pa|psi|lk=on}} (0.1&nbsp;inch of water column) or less.<ref name="design guide" /> UFAD is particularly suitable for buildings with high height ceilings, where the energy saving effect is more pronounced due to thermal stratification.<ref>{{Cite journal |last1=Raftery |first1=Paul |last2=Bauman |first2=Fred |last3=Schiavon |first3=Stefano |last4=Epp |first4=Tom |title=Laboratory testing of a displacement ventilation diffuser for underfloor air distribution systems |journal=Energy and Buildings |year=2015 |language=en |volume=108 |pages=82–91 |doi=10.1016/j.enbuild.2015.09.005|doi-access=free }}</ref> Because UFAD is accomplished by supplying air through a raised floor using different types of distribution configurations and outlets, the key issue for efficient performance of the system is to ensure thermal stratification. The inefficient operation of the UFAD system virtually deteriorated the potential savings presumed from such a system.<ref>{{Cite journal |last1=Alajmi |first1=Ali F. |last2=Abou-Ziyan |first2=Hosny Z. |last3=El-Amer |first3=Wid |date=2013-09-01 |title=Energy analysis of under-floor air distribution (UFAD) system: An office building case study |url=https://www.sciencedirect.com/science/article/pii/S0196890413001908 |journal=Energy Conversion and Management |language=en |volume=73 |pages=78–85 |doi=10.1016/j.enconman.2013.04.003 |issn=0196-8904}}</ref> Also, the investigation of energy saving has shown that this amount varies for buildings located in different climates, suggesting further studies should investigate this factor prior to designing a suitable HVAC system. ==Applications== Underfloor air distribution is frequently used in [[office building]]s, particularly highly-reconfigurable and open plan offices where [[raised floor]]s are desirable for cable management. UFAD is also common in [[command center]]s, [[information technology|IT]] [[data center]]s and [[Server room]]s that have large cooling loads from electronic equipment and requirements for routing power and data cables. The [[ASHRAE]] Underfloor Air Distribution Design Guide suggests that any building considering a [[raised floor]] for cable distribution should consider UFAD.<ref name="design guide">{{Citation | title = Underfloor Air Distribution Design Guide | year = 2003 | journal = ASHRAF | last1 = Bauman | first1 = Fred | last2 = Daly | first2 = Allan}}</ref> Specific space considerations should be taken when using UFAD systems in laboratories because of its critical room pressurization requirements and potential migration of chemicals into the access floor plenum due to spillage. UFAD systems are not recommended in some specific facilities or spaces, such as small non-residential buildings, wet spaces like restrooms and pool areas, kitchens and dining areas and gymnasiums, because UFAD may result in especially difficult or costly in design. UFAD systems may also be used with other HVAC systems, like displacement ventilation, overhead air distribution systems, radiant ceiling or chilled beam systems to get better performance.<ref name = "design guide"/> ==UFAD compared to other distribution systems== {{main|Room air distribution}} ===Overhead (mixing)=== Conventional ''overhead mixing systems'' usually locate both the supply and return air ducts at the ceiling level. Supply air is supplied at velocities higher than typically acceptable for human comfort and the air temperature may be lower, higher, or the same as desired room temperature depending on the cooling/heating load. High-speed turbulent air jets incoming supply air mix with the room air. A well-engineered UFAD systems have several potential advantages over traditional overhead systems, such as layout flexibility, improved thermal comfort, improved ventilation efficiency and indoor air quality, improved energy efficiency in suitable climates and reduced life cycle costs.<ref name="Thermal decay">{{cite journal|last=Kwang Ho|first=Lee|author2=Stefano Schiavon |author3=Fred Bauman |author4=Tom Webster |title=Thermal decay in underfloor air distribution (UFAD) systems: Fundamentals and influence on system performance|journal=Applied Energy|year=2012|volume=91|issue=1|pages=197–207 | doi = 10.1016/j.apenergy.2011.09.011|s2cid=54035654 |url=http://www.escholarship.org/uc/item/6tn9246f}}</ref><ref> {{cite web| url= http://cbe.berkeley.edu/underfloorair/techoverview.htm |title=UFAD Technology Overview |publisher=Center for the Built Environment |access-date=27 Nov 2013 }}</ref> ===Displacement ventilation=== {{main|Displacement ventilation}} ''Displacement Ventilation'' systems (DV) work on similar principals as UFAD systems. DV systems deliver cool air into the conditioned space at or near the floor level and return air at the ceiling level. This works by utilizing the natural [[Stack effect|buoyancy]] of warm air and the thermal plumes generated by heat sources as cooler air is delivered from lower elevations. While similar, UFAD tends to encourage more mixing within the occupied zone and provide local air supply, which enables it to increase air motion in the space and prevent the sensation of stagnant air conditions, often associated with poor air quality. The major practical differences are that in UFAD, air is supplied at a higher velocity through smaller-size supply outlets than in DV, and the supply outlets are usually controlled by the occupants.<ref name = "design guide"/> ==List of notable buildings using UFAD systems== {| class="sortable wikitable" |- style="background:#ececec;" ! Structure ! Year ! Country ! City ! Architects ! Coordinates |- |[[Bank of America Tower (New York City)|Bank of America Tower]] || 2009 || [[New York (state)|NY]] || [[New York City]] || [[Cook+Fox Architects]] || {{coord|40|45|20.6|N|73|59|2.81|W|display=inline}} |- |[[David Brower Center]] || 2009 || [[California|CA]] || [[Berkeley, California|Berkeley]] || [[Solomon E.T.C.-WRT]] || {{coord|37|52|10.97|N|122|15|58.53|W|display=inline}} |- |[[San Francisco Federal Building]] || 2007 || [[California|CA]] || [[San Francisco]] || [[Morphosis]] || {{coord|37|46|47.09|N|122|24|44.13|W|display=inline}} |- |[[IRS|Internal Revenue Service]] || 2007 || [[Missouri|MO]] || [[Kansas City, Missouri|Kansas City]] || [[BNIM]] || {{coord|39|5|11.30|N|94|35|2.35|W|}} |- |[[The New York Times Building]] || 2007 || [[New York (state)|NY]] || [[New York City|New York]] || [[Renzo Piano|Renzo Piano Building Workshop]] || {{coord|40|45|23.42|N|73|59|25.15|W|}} |- |[[Caltrans District 7 Headquarters|Caltrans District 7 HQ]] || 2005 || [[California|CA]] || [[Los Angeles]] || [[Thom Mayne]] || {{coord|34|3|21.75|N|118|14|40.47|W|}} |- |[[CalPERS]] HQ|| 2005 || [[California|CA]] || [[Sacramento]] || [[Pickard Chilton Architects]] || {{coord|38|34|33.51|N|121|30|17.65|W|}} |- |[[Foundry Square]] || 2005 || [[California|CA]] || [[San Francisco]] || [[Studios Architecture|Studios Architecture ''et al.'']] || {{coord|37|47|24.54|N|122|23|49.02|W|}} |- |[[Robert E. Coyle United States Courthouse]] || 2005 || [[California|CA]] || [[Fresno]] || [[Moore Ruble Yudell, Gruen Associates]] || {{coord|36.7377|-119.7838|region:US-CA_type:landmark|display=title,inline}} |- |[[Visteon]] HQ || 2004 || [[Michigan|MI]] || [[Van Buren Township, Wayne County, Michigan|Van Buren Township]] || [[SmithGroup]]JJR || {{coord|42|14|39.61|N|83|25|58.53|W|}} |- |[[Ray and Maria Stata Center]] || 2003 || [[Massachusetts|MA]] || [[Boston]] || [[Frank Gehry]] || {{coord|42|21|43.35|N|71|5|23.26|W|}} |- |[[Hewlett Foundation]] || 2002 || [[California|CA]] || [[Menlo Park, California|Menlo Park]] || [[B.H. Bocook, Architects, Inc]] || {{coord|37|25|30.87|N|122|11|38.04|W|}} |- |[[Bellagio (hotel and casino)|Bellagio Show Palace]] || 1998 || [[Nevada|NV]] || [[Paradise, Nevada|Paradise]] || [[Will Bruder]] || {{coord|36|6|45.10|N|115|10|33.41|W|}} |- |[[Phoenix Public Library]] || 1995 || [[Arizona|AZ]] || [[Phoenix, Arizona|Phoenix]] || [[Will Bruder]] || {{coord|33|28|17.71|N|112|4|23.84|W|}} |- |[[Apple Store]] || 1993 || [[California|CA]] || [[San Francisco]] || [[Bohlin Cywinski Jackson]] || {{coord|37|47|10.16|N|122|24|22.57|W|}} |- |[[Taco Bell]] Headquarters || 2009 || [[California|CA]] || [[Irvine, California|Irvine]] || [[LPA Architects]] || {{coord|33.6571981|-117.7469452|}} |- |[[Pearl River Tower]] |2011 |[[China]] |[[Guangzhou]] |[[Skidmore, Owings & Merrill|SOM]] and [[Adrian Smith + Gordon Gill Architecture|AS+GG]] || {{coord|23|7|36.3|N|113|19|3.36|E|}} |- |[[Manitoba Hydro Tower]] || 2009 || [[Canada]] || [[Winnipeg]], [[Manitoba|MB]] || [[Kuwabara Payne McKenna Blumberg]] || {{coord|49|53|33.99|N|97|8|46.70|W|}} |- |[[Vancouver Public Library]] || 1995 || [[Canada]] || [[Vancouver]], [[British Columbia|BC]] || [[Moshe Safdie]] & DA architects || {{coord|49|16|44.72|N|123|6|57.68|W|}} |- |[[Salesforce Tower]] || 2017 || [[California|CA]] || [[San Francisco]] || [[César Pelli|Pelli Clarke Pelli Architects]] || {{coord|37|47|23.64|N|122|23|48.84|W|display=inline}} |- |} ==References== {{reflist|33em}} ==External links== * [http://cbe.berkeley.edu/research/ufad_techtransfer.htm#symposium Slides from a Center for the Built Environment workshop about UFAD.] * The Center for the Built Environment (CBE), University of California, Berkeley. http://www.cbe.berkeley.edu/ Professional and Trade groups that provide research funding and publish standards or guides regarding UFAD systems include: # [[American Society of Heating, Refrigerating and Air-Conditioning Engineers]], (ASHRAE) http://www.ashrae.org/ # Air-Conditioning and Refrigeration Technology Institute (ARTI) # The Air-Conditioning, Heating, and Refrigeration Institute (AHRI) http://www.ahrinet.org/ {{HVAC}} [[Category:Heating, ventilation, and air conditioning]] [[Category:Building biology]] [[Category:Floor construction]] [[Category:Low-energy building]] [[Category:Environmental design]] [[Category:Ventilation]] </textarea><div class="templatesUsed"><div class="mw-templatesUsedExplanation"><p><span id="templatesused">Pages transcluded onto the current version of this page<span class="posteditwindowhelplinks"> (<a href="/wiki/Help:Transclusion" title="Help:Transclusion">help</a>)</span>:</span> </p></div><ul> <li><a href="/wiki/Template:Citation" title="Template:Citation">Template:Citation</a> (<a href="/w/index.php?title=Template:Citation&action=edit" title="Template:Citation">view source</a>) (protected)</li><li><a href="/wiki/Template:Cite_book" title="Template:Cite book">Template:Cite book</a> (<a href="/w/index.php?title=Template:Cite_book&action=edit" 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